This laboratory has proivided a number of services to Pregnancy Research Branch and other NICHD investigators. The Endocrine Assays Laboratory generated, titered and distributed sheep anti-rabbit gramma globulin sera (second antibody) to NICHD Intramural Investigators, mostly in PRB, ERRB amd DEB. Rigid quality control and efficient harvesting procedures were combined to provide a high quality reagent at a fraction of the comercial cost. Radioimmunoassay procedures for polypeptide and steroid hormones of reproductive interest have been maintained and utilized for research investigations. Teaching of radioimmunoassay methodology for polypeptide and steroid hormones has been provided as required by on-campus and local off-campus requests. In addition, antisera to steroid hormones were provided off-campus investigators.